A standalone dual-pass solar air heater using downspouts

Thanks for your help and comments.

Bill

This system has been in use for more than a month so I thought I'd give an update. Comparisons to last year are pretty valid, since La Nina conditions (generally warmer and drier than normal) prevailed then as now. Still winter-ish though; last night's low 23F, today's high 42F.

There are three main ways I evaluate this project: 1. how well does the heater work, 2. how well is it sized to the space it's heating, and 3. how much is it reducing my wood consumption in that space.

The numbers give #1, the effectiveness of the design, high marks and I do also. On a btus/sq ft basis, it works really well.

In #2 it falls short. But I knew this would be the case. I wanted to build it twice the height but decided there wasn't room for that. At 2'x12" it's undersized for the space, so it can only carry the heat load requirements in the shoulder seasons. On the other hand, it's putting btus into the basement on days where previously none would have been (weekends and holidays), and that is a definite plus.

All that being the case, it is still going to put a significant dent into the wood use downstairs. Here we are at the end of November, and I have only had 5 small fires in the X33 to take a morning chill off. Last year at this time, I was burning a couple loads a day on workdays.

So, overall I'm very pleased with it. There are still improvements to be made. The outdoor vent pipes could be better insulated. At some point, a quieter fan would be nice. And in the back of my mind, I'm thinking this unit could perhaps be put on the roof and piped into the bedroom on the north end, and I'll find a way to put a larger unit in its place...

That's great. How about some current numbers. Or are you still measuring them.

Precaud, glad to see you're still at this.
Do you think there might be a benefit to boxing in/insulating the intake/exhaust runs to further reduce heat losses?
Would that create other problems for you?
Are you using schedule 30 or 40, and I wonder if it would make a difference in heat retention?
This is VERY interesting stuff.

karl, my data logger went on the fritz right after the last set I took, and I haven't found time to fix it yet.

Hi Dave, yes I think there would be real benefit to that. An yes, there is a problem with it, the vent pipes run right next to the only outdoor water outlet, which I can't block access to.

Sorry, I don't know what that is, pls explain.

Sorry, referring to the pvc pipe.....schedule 30 is thin wall and schedule 40 is thicker.
I thought I saw an outdoor spigot.

It's the thinner wall pvc, used for sewer pipe. My thought was, pipe area was more important than thickness. In hindsight, it would have been better to go bigger than 4", but I didn't see any pvc larger than that.